In 2010, there were 70,530 new cases of bladder cancer diagnosed in the United States and 14,680 deaths from bladder cancer. Of the newly diagnosed patients, more than 52,000 were men and 18,000 were women with most male patients above the age of 50. Approximately 70% of these new cases of bladder cancer were classified as non-muscle invasive cancer (NMIBC) which is initially treated with transurethral resection of bladder tumor (TURBT). In addition to being a standard surgical therapy for noninvasive bladder cancer, TURBT is also an integral part of the diagnostic evaluation of all bladder tumors.
FIG. 1 illustrates one example of a bladder resection procedure being performed with a resectoscope. The resectoscope is inserted through the urethra of a patient to access the bladder. Tumors in the bladder wall are resected through to the muscular layer of the bladder. Motion of the resectoscope is limited by the tissue and pubis anterior-superiorly and posterior-inferiorly. Medial and lateral motion is further hampered by the legs of the patient. The inserts in FIG. 1 depicts a tumor with both a broad front invasion in which the extent of the tumor is visible at the surface (A) and tentacular invasion in which the tumor invades below the urothelium and the margin for resection is invisible under white-light based imaging (B).
TURBT does, however, have its shortcomings. Initial TURBT is associated with imperfect clinical staging and incomplete tumor removal. An accurate pathological diagnosis, which is determined by depth of tumor invasion, is crucial for staging urothelial carcinomas. The stage of a patient's bladder cancer plays a key role in determining the patient's treatment and prognosis. The urologist is responsible for accurately sampling bladder tissue for evaluation, and should include muscularis propria (detrusor muscle) for adequate staging. Specimens missing muscle layers cannot confirm complete tumor resection.
The technical challenges of manual TURBT procedures are associated with considerable clinical ramifications. Although TURBT remains the gold standard for initial diagnosis and treatment of NMIBC, the early recurrence rate at three months can be as high as 45%. Furthermore, despite recommendations to perform complete resection of all visible tumors during an initial TURBT, a study of 150 consecutive patients with NMIBC undergoing repeat transurethral resection within 6 weeks of the initial procedure found 76% with residual tumor. Studies also indicate that at up to 5% of all TUR procedures result in perforations in the bladder due to full wall resection.
Furthermore, there is high variability in the clinical outcomes of TURBT procedures based on the skill of the surgeon and the technique used. In a combined analysis of seven randomized studies, the recurrence rate following TURBT for non-muscle invasive bladder cancer varied between institutions from 7% to 45%. This and other studies have been unable to attribute this variation to any other factor and instead conclude that the high variability in success rate is attributable to surgeon technique.
Lesion location can also influence resectability of tumors. In certain areas of the bladder, the ideal angle of approach to a tumor may be kinematically infeasible such that the bladder wall cannot be appropriately reached or traced. As illustrated in FIG. 1, the anatomic constraints of the entrance through the urethra make access to anterior regions of the bladder difficult or infeasible without external manipulation. For approaching anterior aspects of the bladder, suprapubic pressure is applied to bring the bladder wall into the reachable workspace of the rigid resectoscope. However, these techniques have limited success with many patients—particularly in obese patients due to thick fat layers.